1. Field of the Invention
This invention relates to an implement for facilitating the mounting of tires on respective wheel rims, such as to prevent damage to the tire and under conditions of maximum safety for the operator.
2. Description of the Background Art
As is well known, modern tires, removal machines, typically for automobile and other light vehicle wheels and for motorcycle wheels, comprise, inter alia, a horizontal self-centering unit provided for locking the rims of said wheels, and an overlying tool for mounting and removing the respective tires, thus acting between the edge of the wheel rim and the tire bead.
Said tool can be adjusted both vertically and horizontally, in order to adapt its operating position to wheel rims of different widths and diameters.
Specifically, said tool is supported by a vertical rod slidingly mounted at the end of an arm branching from a column situated behind the self-centering unit.
With reference to said column, four different types of tire removal machine are known, namely:
a first type in which the column is fixed to the base of the tire removal machine, PA1 a second type in which the column can swing in a vertical plane passing through the axis of rotation of the self-centering unit, PA1 a third type in which the column can rotate about its own longitudinal axis, and PA1 a fourth type in which the rod support arm is hinged to the column so that it can swing in a horizontal plane. PA1 firstly, the bead is rested on the edge of the wheel rim, PA1 secondly, the mounting tool is inserted between the rim and the bead, PA1 thirdly, the bead is inclined in order to position below said tool and below said wheel rim edge that bead part which, with reference to the direction of rotation (for mounting the tire) of the self-centering unit, lies downstream of said tool, and PA1 finally, the self-centering unit is made to rotate, with the result that the tool inserts the remaining (upstream) part of the bead below the wheel rim edge.
A problem common to all these tire removal machines is that of easily, rapidly and reliably mounting a tire on the respective wheel rim.
The procedure for positioning each individual bead of a tire below the edge of a wheel rim locked onto the self-centering unit, at that moment stationary, is as follows:
However as the mounting tool acts alone, it can subject the bead to difficulties and/or excessive stresses, and hence to possible damage (such as stretching, local weaknesses and cracking), resulting in damage to the tire.
This is due to the fact that that bead part already inserted rests in its final seat without entering the central channel of the wheel rim, which is obviously of smaller diameter.
For this reason, when mounting each individual bead the operator is required to thrust downwards that bead part gradually arriving below the edge of the wheel rim, in order to maintain it within the rim channel.
Said thrust action is normally exerted by hand, in certain cases a lever being used, in particular if the beads are fairly rigid and hence particularly difficult to retain within the wheel rim channel.
However this procedure has unfortunately proved relatively dangerous because the operator is compelled to operate (by hand or via said lever) on parts under movement, and because the said operator often operates on greased surfaces (aimed at facilitating bead insertion).
Moreover, said operations are relatively uncomfortable, relatively burdonsome and relatively lengthy, especially if particularly rigid beads are concerned.
From the aforegoing it is apparent that in this sector there is a requirement for means for obviating the aforelisted problems.
To satisfy said requirements, special devices are known for application to specific types of tire removal machines, their use being therefore very limited.
One of said known devices is illustrated in Utility Model Application No. 34843 B/89 in the name of the present applicant, which reference should be made for further details.